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$$\sum_{p\rm\;prime}f(p) = \int_{t>1}f(t)d\pi(t)$$

$$2\uparrow\uparrow k
\mathrel{\mathop=^{\rm def}}
2^{2^{\cdot^{\cdot^{\cdot^2}}}}
\vbox{\hbox{$\Big\}\scriptstyle k$}\kern0pt}$$

\begin{equation}
 p(y|\mathbf{x}) = \frac{p(\mathbf{x},y)}{p(\mathbf{x})}=
\frac{p(\mathbf{x}|y)p(y)}{p(\mathbf{x})} \label{equ:chap1:bayes}
\end{equation}


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